TLR4 single nucleotide polymorphisms (SNPs) associated with Salmonella shedding in pigs.

Toll-like receptor 4 (TLR4) is a key factor in the innate immune recognition of lipopolysaccharide (LPS) from Gram-negative bacteria. Previous studies from our group identified differences in the expression profile of TLR4 and genes affected by the TLR4 signaling pathway among pigs that shed varying levels of Salmonella, a Gram-negative bacterium. Therefore, genetic variation in this gene may be involved with the host's immune response to bacterial infections.

Distinct peripheral blood RNA responses to Salmonella in pigs differing in Salmonella shedding levels: intersection of IFNG, TLR and miRNA pathways.

Transcriptomic analysis of the response to bacterial pathogens has been reported for several species, yet few studies have investigated the transcriptional differences in whole blood in subjects that differ in their disease response phenotypes. Salmonella species infect many vertebrate species, and pigs colonized with Salmonella enterica serovar Typhimurium (ST) are usually asymptomatic, making detection of these Salmonella-carrier pigs difficult. The variable fecal shedding of Salmonella is an important cause of foodborne illness and zoonotic disease.

Use of bioinformatic SNP predictions in differentially expressed genes to find SNPs associated with Salmonella colonization in swine.

Asymptomatic Salmonella-carrier pigs present a major problem in preharvest food safety, with a recent survey indicating >50% of swine herds in the United States have Salmonella-positive animals. Salmonella-carrier pigs serve as a reservoir for contamination of neighbouring pigs, abattoir pens and pork products. In addition, fresh produce as well as water can be contaminated with Salmonella from manure used as fertilizer.

Integrating comparative expression profiling data and association of SNPs with Salmonella shedding for improved food safety and porcine disease resistance.

Salmonella in swine is a major food safety problem, as the majority of US swine herds are Salmonella-positive. Salmonella can be shed from colonized swine and contaminate (i) neighbouring pigs; (ii) slaughter plants and pork products; (iii) edible crops when swine manure is used as a fertilizer; and (iv) water supplies if manure used as crop fertilizer runs off into streams and waterways. A potentially powerful method of addressing pre-harvest food safety at the farm level is through genetic improvement of disease resistance in animals.

Methods for transcriptomic analyses of the porcine host immune response: application to Salmonella infection using microarrays.

Technological developments in both the collection and analysis of molecular genetic data over the past few years have provided new opportunities for an improved understanding of the global response to pathogen exposure. Such developments are particularly dramatic for scientists studying the pig, where tools to measure the expression of tens of thousands of transcripts, as well as unprecedented data on the porcine genome sequence, have combined to expand our abilities to elucidate the porcine immune system. In this review, we describe these recent developments in the context of our work using primarily microarrays to explore gene expression changes during infection of pigs by Salmonella.